Name: in vesiculo synthesis of peptide membrane precursors for autonomous vesicle growth
Uploaded: 2019-06-28T14:10:00
Description: Watch this Scientific Journal Video about In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth at JoVE.com

We gratefully acknowledge financial support through the DFG TRR 235 (Emergence of Life, project P15), the European Research Council (grant agreement no. 694410 AEDNA), and the TUM International Graduate School for Science and Engineering IGSSE (project no. 9.05). We thank E. Falgenhauer for her help with sample preparation. We thank A. Dupin and M. Schwarz-Schilling for their help with the TX-TL system and useful discussions. We thank N. B. Holland for useful discussions.

1. Expression of Elastin-like Polypeptides
<ol>
	<li>Day 1: Preparation of a starter culture and supplies for peptide expression
	<ol>
		<li>Prepare and autoclave expression culture flasks (4 x 2.5 L) and 3 L of LB medium. For 1 L of LB medium, add 25 g of LB powder to 1 L of ultrapure water.</li>
		<li>Prepare a starter culture with 100 mL of LB medium, 50 &#181;L of sterile-filtered (0.22 &#181;m filter) chloramphenicol solution (25 mg/mL in EtOH), and 50 &#181;L of sterile-filtered (0.22 &#181;m fil...

<ol>
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E., Chilkoti, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+encoded+synthesis+of+protein-based+polymers+with+precisely+specified+molecular+weight+and+sequence+by+recursive+directional+ligation:+examples+from+the+elastin-like+polypeptide+system.">Genetically encoded synthesis of protein-based polymers with precisely specified molecular weight and sequence by recursive directional ligation: examples from the elastin-like polypeptide system.</a> Biomacromolecules. 3 (2), 357-367 (2002).</li><li>Sun, Z. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protocols+for+implementing+an+Escherichia+coli+based+TX-TL+cell-free+expression+system+for+synthetic+biology.">Protocols for implementing an Escherichia coli based TX-TL cell-free expression system for synthetic biology.</a> Journal of Visualized Experiments. (79), e50762 (2013).</li><li>Caschera, F., Noireaux, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+2.3+mg/ml+of+protein+with+an+all+Escherichia+coli+cell-free+transcription-translation+system.">Synthesis of 2.3 mg/ml of protein with an all Escherichia coli cell-free transcription-translation system.</a> Biochimie. 99, 162-168 (2014).</li><li>Schwarz-Schilling, M., Aufinger, L., M&#252;ckl, A., Simmel, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+communication+between+bacteria+and+cell-free+gene+expression+systems+within+linear+chains+of+emulsion+droplets.">Chemical communication between bacteria and cell-free gene expression systems within linear chains of emulsion droplets.</a> Integrative Biology. 8 (4), 564-570 (2016).</li><li>Garamella, J., Marshall, R., Rustad, M., Noireaux, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+All+E.+coli+TX-TL+Toolbox+2.0:+A+Platform+for+Cell-Free+Synthetic+Biology.">The All E. coli TX-TL Toolbox 2.0: A Platform for Cell-Free Synthetic Biology.</a> ACS Synthetic Biology. 5 (4), 344-355 (2016).</li><li>Rideau, E., Dimova, R., Schwille, P., Wurm, F. R., Landfester, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liposomes+and+polymersomes:+a+comparative+review+towards+cell+mimicking.">Liposomes and polymersomes: a comparative review towards cell mimicking.</a> Chemical Society Reviews. 47 (23), 8572-8610 (2018).</li><li>Filonov, G. S., Moon, J. D., Svensen, N., Broccoli Jaffrey, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Broccoli:+Rapid+Selection+of+an+RNA+Mimic+of+Green+Fluorescent+Protein+by+Fluorescence-Based+Selection+and+Directed+Evolution.">Broccoli: Rapid Selection of an RNA Mimic of Green Fluorescent Protein by Fluorescence-Based Selection and Directed Evolution.</a> Journal of the American Chemical Society. 136 (46), 16299-16308 (2014).</li><li>Zhang, S., Cahalan, M. 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Film rehydration is a common procedure for the creation of small unilamellar vesicles. The main source of failure is the wrong handling of the materials used in the procedure.

Initially, the ELPs are produced by E. coli cells. The yield after ELP purification can vary significantly depending on how carefully the protocol is conducted during its crucial steps. These are the inverse temperature cycling (ITC) step and th...

The creation of synthetic living cellular systems is usually approached from two different directions. In the top-down method, the genome of a bacterium is reduced to its essential components, ultimately leading to a minimal cell. In the bottom-up approach, artificial cells are assembled de novo from molecular components or cellular subsystems, which need to be functionally integrated into a consistent cell-like system.
In the de novo approach, compartmentalization of the necessary biochemical components is usually achieved using membranes made from phospholipids or fatty acids1,2,3,4. This is because &#34;modern&#34; cell membranes mainly consist of phospholipids, while fatty acids are regarded plausible candidates of prebiotic membrane enclosures5,6. For the formation of new membranes or to facilitate membrane growth, amphiphilic building blocks must be provided from the exterior7 or ideally through production within a membranous compartment using the corresponding anabolic processes4,8.
While lipid synthesis is a relatively complex metabolic process, peptides can be produced quite readily using cell-free gene expression reactions9,10. Hence, peptide membranes formed by amphiphilic peptides represent an interesting alternative to lipid membranes as enclosures for artificial cell mimics that are able to grow11.
Amphiphilic elastin-like di-block copolymers (ELPs) are an attractive class of peptides, which can serve as the building block for such membranes12. The basic amino acid sequence motif of ELPs is (GaGVP)n, where &#8220;a&#8221; can be any amino acid except for proline and &#8220;n&#8221; is the number of motif repeats13,14,15,16,17. ELPs have been created with a hydrophobic block containing mainly phenylalanine for a and a hydrophilic block mainly composed of glutamic acid11. Depending on a and solution parameters, such as pH and salt concentration, ELPs exhibit a so-called inverse temperature transition at temperature Tt, where the peptides undergo a fully reversible phase transition from a hydrophilic to hydrophobic state. The synthesis of the peptides can be easily implemented inside vesicles using the &#8220;TX-TL&#8221; bacterial cell extract11,18,19,20,21, which provides all necessary components for coupled transcription and translation reactions.
The TX-TL system was encapsulated together, with the DNA template encoding the ELPs into ELP vesicles utilizing dehydration-rehydration from glass beads as a solid support. The formation of vesicles occurs through rehydration of the dried peptides from the bead surface11. Other methods22 for vesicle formation can be used, which potentially show lower polydispersity and larger vesicle sizes (e.g., electro-formation, emulsion phase transfer, or microfluidics-based methods). To test the viability of the encapsulation method, transcription of the fluorogenic aptamer dBroccoli23 can alternatively be used11, which is less complex than gene expression with the TX-TL system.
Due to the expression of the membrane building blocks in vesiculo and their subsequent incorporation into the membrane, the vesicles start to grow11. Membrane incorporation of the ELPs can be demonstrated through a FRET assay. To this end, the ELPs used for formation of the initial vesicle population are be conjugated with fluorescent dyes in equal shares constituting a FRET pair. Upon expression of non-labeled ELPs in vesiculo and their incorporation into the membrane, the labeled ELPs in the membrane are diluted and consequently the FRET signal decreases11. As a versatile and common method for conjugation, copper catalyzed azide-alkyne cycloaddition is used. With the use of a stabilizing ligand such as tris(benzyltriazolylmethyl)-amine, the reaction can be carried out in an aqueous solution at a physiological pH without the hydrolysis of reactants11, which is appropriate for conjugation reactions involving peptides.
The following protocol presents a detailed description of the preparation for growing ELP-based peptidosomes. The expression of the peptides and vesicle formation using the glass beads method are described. Furthermore, it is described how to implement transcription of the fluorogenic dBroccoli aptamer and the transcription-translation reaction for protein expression inside the ELP vesicles. Finally, provided is a procedure for the conjugation of ELPs with fluorophores, which can be used to prove vesicle growth through a FRET assay11.

<table>
	<tbody>
		<tr>
			<td>2xYT</td>
			<td>MP biomedicals</td>
			<td>3012-032</td>
			<td></td>
		</tr>
		<tr>
			<td>3-PGA</td>
			<td>Sigma-Aldrich</td>
			<td>P8877</td>
			<td></td>
		</tr>
		<tr>
			<td>5PRIME Phase Lock GelTM tube</td>
			<td>VWR</td>
			<td>733-2478</td>
			<td></td>
		</tr>
		<tr>
			<td>alkine-conjugated Cy3</td>
			<td>Sigma-Aldrich</td>
			<td>777331</td>
			<td></td>
		</tr>
		<tr>
			<td>alkine-conjugated Cy5</td>
			<td>Sigma-Aldrich</td>
			<td>777358</td>
			<td></td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>Sigma-Aldrich</td>
			<td>A8937</td>
			<td></td>
		</tr>
		<tr>
			<td>benzamidin</td>
			<td>Carl Roth</td>
			<td>CN38.2</td>
			<td></td>
		</tr>
		<tr>
			<td>BL21 Rosetta 2 E. coli strain</td>
			<td>Novagen</td>
			<td>71402</td>
			<td></td>
		</tr>
		<tr>
			<td>Bradford BSA Protein Assay Kit</td>
			<td>Bio-rad</td>
			<td>500-0201</td>
			<td></td>
		</tr>
		<tr>
			<td>cAMP</td>
			<td>Sigma-Aldrich</td>
			<td>A9501</td>
			<td></td>
		</tr>
		<tr>
			<td>carbenicillin</td>
			<td>Carl Roth</td>
			<td>6344.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloramphenicol</td>
			<td>Sigma-Aldrich</td>
			<td>C1919</td>
			<td></td>
		</tr>
		<tr>
			<td>chloramphenicol</td>
			<td>Carl Roth</td>
			<td>3886.3</td>
			<td></td>
		</tr>
		<tr>
			<td>chloroform</td>
			<td>Carl Roth</td>
			<td>4432.1</td>
			<td></td>
		</tr>
		<tr>
			<td>CoA</td>
			<td>Sigma-Aldrich</td>
			<td>C4282</td>
			<td></td>
		</tr>
		<tr>
			<td>CTP</td>
			<td>USB</td>
			<td>14121</td>
			<td></td>
		</tr>
		<tr>
			<td>CuSO4</td>
			<td>Carl Roth</td>
			<td>P024.1</td>
			<td></td>
		</tr>
		<tr>
			<td>DFHBI</td>
			<td>Lucerna Technologies</td>
			<td>410</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Carl Roth</td>
			<td>A994.1</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>NEB</td>
			<td>M0303S</td>
			<td></td>
		</tr>
		<tr>
			<td>DTT</td>
			<td>Sigma-Aldrich</td>
			<td>D0632</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Carl Roth</td>
			<td>9065.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Folinic acid</td>
			<td>Sigma-Aldrich</td>
			<td>F7878</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass beads, acid-washed</td>
			<td>Sigma-Aldrich</td>
			<td>G1277</td>
			<td></td>
		</tr>
		<tr>
			<td>GTP</td>
			<td>USB</td>
			<td>16800</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H6147</td>
			<td></td>
		</tr>
		<tr>
			<td>IPTG (&#946;-isopropyl thiogalactoside )</td>
			<td>Sigma-Aldrich</td>
			<td>I6758</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Carl Roth</td>
			<td>P017.1</td>
			<td></td>
		</tr>
		<tr>
			<td>K-glutamate</td>
			<td>Sigma-Aldrich</td>
			<td>G1149</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Broth</td>
			<td>Carl Roth</td>
			<td>X968.2</td>
			<td></td>
		</tr>
		<tr>
			<td>lysozyme</td>
			<td>Sigma-Aldrich</td>
			<td>L6876</td>
			<td></td>
		</tr>
		<tr>
			<td>methanol</td>
			<td>Carl Roth</td>
			<td>82.2</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Carl Roth</td>
			<td>KK36.3</td>
			<td></td>
		</tr>
		<tr>
			<td>Mg-glutamate</td>
			<td>Sigma-Aldrich</td>
			<td>49605</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Bio-Spin Chromatography Columns</td>
			<td>Bio-Rad</td>
			<td>732-6204</td>
			<td></td>
		</tr>
		<tr>
			<td>NAD</td>
			<td>Sigma-Aldrich</td>
			<td>N6522</td>
			<td></td>
		</tr>
		<tr>
			<td>NHS-azide linker (y-azidobutyric acid oxysuccinimide ester)</td>
			<td>Baseclick</td>
			<td>BCL-033-5</td>
			<td></td>
		</tr>
		<tr>
			<td>PEG-8000</td>
			<td>Carl Roth</td>
			<td>263.2</td>
			<td></td>
		</tr>
		<tr>
			<td>pH stripes</td>
			<td>Carl Roth</td>
			<td>549.2</td>
			<td></td>
		</tr>
		<tr>
			<td>phenylmethylsulfonyl fluoride</td>
			<td>Carl Roth</td>
			<td>6367.2</td>
			<td></td>
		</tr>
		<tr>
			<td>phosphate-buffered saline</td>
			<td>VWR</td>
			<td>76180-684</td>
			<td></td>
		</tr>
		<tr>
			<td>phosphoric acid</td>
			<td>Sigma-Aldrich</td>
			<td>W290017</td>
			<td></td>
		</tr>
		<tr>
			<td>polyethyleneimine</td>
			<td>Sigma-Aldrich</td>
			<td>408727</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium phosphate dibasic solution</td>
			<td>Sigma-Aldrich</td>
			<td>P8584</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic solution</td>
			<td>Sigma-Aldrich</td>
			<td>P8709</td>
			<td></td>
		</tr>
		<tr>
			<td>Qiagen Miniprep Kit</td>
			<td>Qiagen</td>
			<td>27106</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAPol reaction buffer</td>
			<td>NEB</td>
			<td>B9012</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase inhibitor murine</td>
			<td>NEB</td>
			<td>M0314S</td>
			<td></td>
		</tr>
		<tr>
			<td>RNaseZap Wipes</td>
			<td>ThermoFisher</td>
			<td>AM9788</td>
			<td></td>
		</tr>
		<tr>
			<td>rNTP</td>
			<td>NEB</td>
			<td>N0466S</td>
			<td></td>
		</tr>
		<tr>
			<td>Roti-Phenol/Chloroform/Isoamyl alcohol</td>
			<td>Carlroth</td>
			<td>A156.1</td>
			<td></td>
		</tr>
		<tr>
			<td>RTS Amino Acid Sampler</td>
			<td>5 Prime</td>
			<td>2401530</td>
			<td></td>
		</tr>
		<tr>
			<td>Slide-A-Lyzer Dialysis Cassettes, 10k MWCO (Kit)</td>
			<td>Thermo-Scientific</td>
			<td>66382</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium chloride</td>
			<td>Carl Roth</td>
			<td>9265.1</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium hydroxide</td>
			<td>Carl Roth</td>
			<td>8655.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Spermidine</td>
			<td>Sigma-Aldrich</td>
			<td>85558</td>
			<td></td>
		</tr>
		<tr>
			<td>sterile-filtered (0.22 &#181;m filter)</td>
			<td>Carl Roth</td>
			<td>XH76.1</td>
			<td></td>
		</tr>
		<tr>
			<td>T7 polymerase</td>
			<td>NEB</td>
			<td>M0251S</td>
			<td></td>
		</tr>
		<tr>
			<td>TBTA (tris(benzyltriazolylmethyl)amine)</td>
			<td>Sigma-Aldrich</td>
			<td>678937</td>
			<td></td>
		</tr>
		<tr>
			<td>TCEP (tris(2-carboxyethyl)-phosphine hydrochloride)</td>
			<td>Sigma-Aldrich</td>
			<td>C4706</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris base</td>
			<td>Fischer</td>
			<td>BP1521</td>
			<td></td>
		</tr>
		<tr>
			<td>tRNA (from E. coli)</td>
			<td>Roche Applied Science</td>
			<td>MRE600</td>
			<td></td>
		</tr>
		<tr>
			<td>UTP</td>
			<td>USB</td>
			<td>23160</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vesiculo synthesis of peptide membrane precursors for autonomous vesicle growth

Compartmentalization of biochemical reactions is a central aspect of synthetic cells. For this purpose, peptide-based reaction compartments serve as an attractive alternative to liposomes or fatty acid-based vesicles. Externally or within the vesicles, peptides can be easily expressed and simplify the synthesis of membrane precursors. Provided here is a protocol for the creation of vesicles with diameters of ~200 nm based on the amphiphilic elastin-like polypeptides (ELP) utilizing dehydration-rehydration from glass beads. Also presented are protocols for bacterial ELP expression and purification via inverse temperature cycling, as well as their covalent functionalization with fluorescent dyes. Furthermore, this report describes a protocol to enable the transcription of RNA aptamer dBroccoli inside ELP vesicles as a less complex example for a biochemical reaction. Finally, a protocol is provided, which allows in vesiculo expression of fluorescent proteins and the membrane peptide, whereas synthesis of the latter results in vesicle growth.

Vesicle production 
Figure 1 shows transmission electron microscopy (TEM) images of vesicles prepared with different swelling solutions and the glass beads method (also see Vogele et al.11). For the sample in Figure 1A, only PBS was used as swelling solution to prove the formation of vesicles and to determine their size. When TX-TL was used as swelling solution (Figure 1B), the vesicles ...

Watch this Scientific Journal Video about In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth at JoVE.com

In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth

Presented here are protocols for the creation of peptide-based small unilamellar vesicles capable of growth. To facilitate in vesiculo production of the membrane peptide, these vesicles are equipped with a transcription-translation system and the peptide-encoding plasmid.

Compartmentalization of biochemical reactions is a central aspect of synthetic cells. For this purpose, peptide-based reaction compartments serve as an ...

In our protocol, we use film re-hydration from small glass beads to form reaction compartments made of peptides. In experiments, we benefit from the protocol's simplicity and robustness. The main advantage of this technique is the ability to incorporate even sensitive samples, such as the used crude cell extract.Contact with organic solvents will significantly affect the sample. To begin this procedure, use a centrifugal vacuum concentrator to concentrate the ELP solution to 1.1 millimolar. Mix 200 microliters of this concentrated solution with 1, 250 microliters of a two to one chloroform and methanol mixture.Vortex the solution to mix thoroughly. Next, add 1.5 grams of spherical glass beads to a ten milliliter round bottom flask. Add the ELP and chloroform methanol solution to the round bottom flask, and gently shake to mix.Connect the flask to a rotary evaporator. Adjust the speed to 150 RPM and regulate the pressure to 20, 000 pascals for approximately four minutes, until the liquid is evaporated at room temperature. It's important to be careful when using the rotary evaporator due to possible boiling retardation.After this, loosely wrap aluminum foil around the opening of the round bottom flask to prevent the loss of glass beads and place the flask into a desiccator for at least one hour, to ensure that the remaining chloroform and methanol are evaporated. For a single experiment, mix 100 milligrams of the peptide covered glass beads with 60 microliters of a swelling solution. Incubate this sample at 25 degrees Celsius for five minutes.Use a table top centrifuge to centrifuge the samples quickly and sediment the glass beads. Then use a pipette to collect the supernatant, which contains the vesicles. First, mix 100 microliters of the pre-purified plasmid DNA with 100 microliters of either Roti-Phenol, chloroform, or isoamyl alcohol in a micro centrifuge tube to enable better phase separation.Gently invert the tube up to six times and centrifuge at 16, 000 times g and room temperature for five minutes. Then, add 200 microliters of chloroform to the upper phase, and invert the tube up to six times. Centrifuge the sample at 16, 000 times g and room temperature for five minutes.After this, pipette the supernatant to a separate tube and add 10 microliters of three molar sodium acetate for ethanol precipitation. Add one milliliter of cold ethanol at 80 degrees Celsius and store the sample at 80 degrees Celsius for one hour. Next, centrifuge the sample at 16, 000 times g and four degrees Celsius for 15 minutes.Decant the supernatant and add one milliliter of cold 70%ethanol at 20 degrees Celsius. Centrifuge at 16, 000 times g and four degrees Celsius for five minutes. Then, remove the liquid by pipetting, being careful to not disturb the DNA pellet.Store the sample at room temperature for approximately 15 minutes to evaporate the remaining ethanol. After this, add ultra pure water to the sample to adjust the sample concentration to approximately 300 nanomolar, which is measured by absorption at 260 nanometers. To prepare the transcription-translation reaction, follow the prepared crude cell extraction and the reaction buffer on ice.For a 60 microliter reaction mix, add the plasma DNA to 37.5 microliters of the reaction buffer, add 28.7 microliters of crude cell extract and fill with ultra pure water to a final volume of 58.8 microliters. Right before the reaction starts, add 1.2 microliters of the T7RNA polymerase solution, and pipette up and down to mix. Incubate the sample and a swelling solution at 29 degrees Celsius for the duration of the experiment, which is typically four to eight hours.Transmission electron microscopy images of vesicles show that various swelling solutions, such as TX/TL or even only PBS can be used to form vesicles. For both solutions, size determination is a straight forward step. Dynamic light scattering shows that vesicles prepared without the glass beads method result in a diameter of 134 nanometers, with a polydispersity of 25%When glass beads are used, the diameter results in 168 nanometers, with a polydispersity of 21%The fluorescence intensity of two fluorescent proteins, which are expressed inside the ELP vesicles, are then measured using a fluorescence plate reader.It is important to note that after vesicle formation, the contents of the vesicles and the outer solution are the same, thus, the antibiotic Kanamycin is added to the exterior solution to suppress protein expression. As a control, Kanamycin is also added to the swelling solution, in which case protein expression inside of the vesicle is suppressed. This indicates that Kanamycin does not diffuse through the membrane, and suppresses internal expression constantly, all the time.The FRET assay is then performed to demonstrate ELP incorporation into the membrane. Upon expression of the membrane ELPs, additional peptides incorporate into the membrane, which increases the average distance between the FRET pairs, and which results in an increase of donor signal. The presented technique can be used to produce simple reaction containers or to create artificial cells with peptide-based membranes.The content inside can be chosen as needed. By using these peptide vesicles, we can now look forward on more complex synthesis reactions within them.

Research

JoVE Journal

Bioengineering

Axon Stretch Growth: The Mechanotransduction of Neuronal Growth

During pre-synaptic embryonic development, neuronal processes traverse short distances to reach their targets via growth cone. Over time, neuronal somata ...

Gold Nanostar Synthesis with a Silver Seed Mediated Growth Method

The physical, chemical and optical properties of nano-scale colloids depend on their material composition, size and shape 1-5. There is a great interest ...

Cultivation of Human Neural Progenitor Cells in a 3-dimensional Self-assembling Peptide Hydrogel

The  influence of 3-dimensional (3D) scaffolds on growth, proliferation and finally  neuronal differentiation is of great interest in order to find new ...

Generation and Recovery of &beta;-cell Spheroids From Step-growth PEG-peptide Hydrogels

Generation and Recovery of &#946;-cell Spheroids From Step-growth PEG-peptide Hydrogels

Hydrogels are hydrophilic crosslinked polymers that provide a three-dimensional  microenvironment with tissue-like elasticity and high permeability for  ...

Lipid Bilayer Vesicle Generation Using Microfluidic Jetting

Bottom-up synthetic biology presents a novel approach for investigating and reconstituting biochemical systems and, potentially, minimal organisms. This ...

Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles

In cardiac myocytes a complex network of membrane tubules - the transverse-axial tubule system (TATS) - controls deep intracellular signaling functions. ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Polyelectrolyte Complex for Heparin Binding Domain Osteogenic Growth Factor Delivery

During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone ...

Synthesis of Monocyte-targeting Peptide Amphiphile Micelles for Imaging of Atherosclerosis

Atherosclerosis is a major contributor to cardiovascular disease, the leading cause of death worldwide, which claims 17.3 million lives annually. ...

Visualization of Germinosomes and the Inner Membrane in Bacillus subtilis Spores

Visualization of Germinosomes and the Inner Membrane in Bacillus subtilis Spores

The small size of spores and the relatively low abundance of germination proteins, cause difficulties in their microscopic analyses using epifluorescence ...